John Gill Commentary 2 Samuel 3:4

"and the fourth, Adonijah the son of Haggith; and the fifth, Shephatiah the son of Abital;" — 2 Samuel 3:4 (ASV)

And the fourth, Adonijah the son of Haggith
The same that usurped the throne before his father's death, to anticipate Solomon, and died by his order, (1 Kings 1:5) (2:25) ;

and the fifth, Shephatiah the son of Abital ;
of whom we read nowhere else.